The basic details of a grain elevator for a combine harvester are disclosed in U.S. Patent No. 2015/0366140 to Strnad, which is incorporated by reference herein in its entirety. As described in U.S. Patent No. 2015/0366140, while referring to prior art FIG. 1, when harvesting crops with an agricultural harvester combine 10, the crop being harvested is cut or collected as the combine traverses the field, by the header 12 mounted to the forward end of the combine 10. The header 12 feeds the crop into the feeder house 14 which carries the crop to the thresher, indicated generally by reference numeral 16 within the interior of the combine 10. The thresher 16 removes the grain from the plant material (e.g., the stalk, cob, pods or other plant material depending on the crop being harvested). The threshed grain then passes through sieves, indicated generally by reference numeral 18, which separate the grain from the unwanted plant debris. The unwanted plant debris is passed toward the back of the combine where it is discharged.
The sieved “clean” grain is directed toward and is collected at the bottom of the clean grain elevator 22. The clean grain elevator 22 lifts the collected clean grain upward into a discharge area 24. An auger 26 within the discharge area 24 carries the grain into a holding tank or hopper 28. As the hopper 28 begins to fill, the grain is unloaded as needed by the unloading auger 30 into a waiting grain cart, wagon, truck or other transport (not shown).
Referring to prior art FIGS. 1 and 2, the clean grain elevator 22 is disposed within a housing 32 and is comprised of a chain 34 which passes around upper and lower sprockets 36, 38. A plurality of equally spaced flights or paddles 40 are attached to the chain 34. As the chain 34 is rotated by the sprockets 36, 38 the paddles 40 scoop the grain being collected at the bottom of the elevator 32 and lift it upward toward the top of the elevator housing 32. As the paddles 40 pass over the upper sprocket 36, the grain is thrown into the discharge area 24 as illustrated in FIG. 2.
The paddle design suffers from at least two drawbacks. First, the paddles 40 tends to rotate (tip or tilt) rearward under the weight of the grain. In other words, the material load on an elevator paddle 40 is multiplied by the length of the paddle 40, which creates a moment that tends to tip the paddle 40 rearward, causing material to roll off of the paddle, thereby reducing conveyor efficiency. Low chain tension and round seeds exacerbates this problem. The resistance to the moment comes from the chain links to which the paddles 40 are attached. For the paddles 40 of FIGS. 1 and 2, the resisting moment may be equal to the moment arm (one link) multiplied by the chain tension.
Second, the rivets connecting the paddle 40 to the chain 34 are subject to fatigue due to the weight of the grain.
In view of the foregoing, there exists a need for an improved paddle having a reduced tendency to tip rearward and suffer from fatigue.